Tie-ups with companies and tourism agencies have elevated the business from side-project to full-time job. It now earns up to $15,000 (£11,353) a month.

Johnston is one of a slew of digital media influencers reshaping the millennial tourism market.

The age group - loosely defined as those born from the early 1980's to 2000 - spends around $200bn (£153bn) on travel each year, according to market research firm FutureCast.

And overall, they have more cash to splash than any previous generation, with around $6tn in disposable income, according to market research firm Asia Insight.

Often cast as fickle and self-absorbed, the generation has been criticised for burning their money on lifestyle perks like avocado toast rather than saving to buy a house, but that tendency to spend is good news for tourism.

And a growing number of travel firms are trying to get a slice of the market.

Image copyrightTriphackrImage caption
People of all ages would likely enjoy a luxury holiday on a tropical island

All around holiday firms are touching up their brands with millennial buzz words - connected, experiential, authentic - in the hope of snaring younger customers.